For example, Patent Literature 1 discloses a filler-pipe attachment structure for attaching a filler pipe to a fuel tank. The conventional filler-pipe attachment structure is mainly constituted by an inlet check valve and a filler tube. The inlet check valve is inserted into an opening of the fuel tank, and the filler tube is fitted onto an outer circumferential surface of an end of the inlet check valve. (Hereinafter, the inlet check valve may be referred to as an ICV.) The filler tube is a connection member having a cylindrical shape and being provided for connecting the filler pipe to the ICV.
A flange which radially protrudes outward is formed on the ICV, and is welded to a surface around the opening of the fuel tank. However, in the above structure, there is a possibility that hydrocarbon penetrates through the boundary between the inner circumferential surface of the filler tube and the outer circumferential surface of the ICV. Specifically, the penetration amount of hydrocarbon is increased by the penetration of hydrocarbon through the boundary between the inner circumferential surface of the filler tube and the outer circumferential surface of the ICV. In addition, the necessity of the filler tube increases the number of parts.
The filler-pipe attachment structure 100 illustrated in FIGS. 3A and 3B is conventionally known as a solution of the above problems. FIGS. 3A and 3B include diagrams illustrating the conventional filler-pipe attachment structure, where FIG. 3A is a perspective diagram, and FIG. 3B is a magnified view of an essential portion. As illustrated in FIG. 3A, the conventional filler-pipe attachment structure 100 is constituted by an ICV 101 and a filler pipe 110. The ICV 101 is inserted through an opening FTa of the fuel tank FT, and the filler pipe 110 is inserted into an end of the ICV 101.
In the ICV 101, as illustrated in FIG. 3B, the ICV 101 includes an inserted portion 102, a protruding portion 103, a concave groove 104, and a rising portion 105. The inserted portion 102 is inserted inside the fuel tank FT. The protruding portion 103 protrudes to the outside of the opening FTa. The concave groove 104 is fitted to an edge portion of the opening FTa. The rising portion 105 rises parallel to the protruding portion 103 from a groove wall of the concave groove 104. On the other hand, a flange 111 radially protruding outward and being perpendicular to the axial direction of the filler pipe 110 is formed at an end of the filler pipe 110.
In assembly of the filler-pipe attachment structure 100, a face FTb of the fuel tank FT and the rising portion 105 are welded to an opposed face 112 of the flange 111 after the concave groove 104 of the ICV 101 is assembled to the opening FTa.